This might be of interest….
Duration of Stretch Does Not Influence the Degree of Force Loss
Following Static Stretching
Source NSCA Conference Abstracts
J.P. Brandenburg, R. West, Applied Neuromuscular Lab, Northern
Illinois University, DeKalb, IL.
There is an emerging body of knowledge consistently indicating
static stretching (SS) acutely and adversely affects muscle
performance. The practical value of this research is questionable
considering the lengthy stretch durations utilized by much of this
literature. It is unclear if stretch durations typical of those used
pre-performance would similarly affect muscle performance.
Additionally, there is a paucity of research examining if a dose-
response relationship exists between stretch duration and the degree
of muscle impairment.
PURPOSE: To determine if SS, using stretch durations more
representative of pre-event routines, affects force production and to
establish if any changes in muscle performance were influenced by the
duration of stretch.
METHODS: Following 2 familiarization sessions, 16 recreationally
trained males and females participated in 2 randomly ordered testing
sessions. In each testing session maximal effort hamstring
performance was assessed prior to and immediately after one of two SS
protocols. During one of the SS protocols participants were required
to hold each stretch for 15s (15S) while stretch duration in the
second SS protocol was 30s (30S). Both SS protocols consisted of 3
repetitions of 2 stretching exercises. A Kincom isokinetic
dynamometer was used to assess hamstring performance during
isometric, concentric, and eccentric actions. Testing velocity during
the dynamic actions was 120 deg*s−1.
RESULTS: Isometric force decreased from 241.8 ± 60N to 227.0 ± 60N
following 30S and from 240.1 ± 50.6N to 225.0 ± 52N after 15S. In
response to 15S and 30S, concentric peak torque fell from 133.5 ±
34Nm to 129 ± 33.7Nm and from 138.8 ± 33Nm to 134.9 ± 33Nm,
respectively. Peak eccentric torque in response to 15S was reduced
from 127.8 ± 35Nm to 121.0 ± 33Nm and from 124.8 ± 32Nm to 117.5 ±
33Nm in response to 30S. For each muscle action, a repeated measures
ANOVA revealed a significant main effect of time (pre- vs. post-
stretch, p < 0.05) but no interaction effect (time ?? SS protocol).
CONCLUSION: SS protocols using stretch durations typical of those
employed in pre-event preparation are sufficient to impair muscle
performance and the duration of stretch did not influence the loss in
force. PRACTICAL APPLICATION: Inclusion of SS, even with short
stretch durations (i.e. 15s), in preparation for strength activities
is not appropriate.